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Coastal Erosion in Southern California Enhanced by the 1997-1998 El Niño. By Zachary Moody. Outline. Background on Erosion Background on 1997-1998 El Niño Measuring Coastal Erosion LiDAR Technology Case Examples from 1997-1998 Human Involvement. Typical California Coastline.
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Coastal Erosion in Southern California Enhanced by the 1997-1998 El Niño By Zachary Moody
Outline • Background on Erosion • Background on 1997-1998 El Niño • Measuring Coastal Erosion • LiDAR Technology • Case Examples from 1997-1998 • Human Involvement
1997-1998 El Niño Global Effects • Began earlier than normal and peaked in January • Temperatures >4o than normal in eastern Pacific and in some areas >9o • Drought and wildfires in Indonesia • Increased number of hurricanes off of Mexico’s coast • 2100 deaths and $33 billion in property damage worldwide www.cnn.com/WEATHER/9708/20/el.nino/
1997-1998 El Niño Effects in the United States • Killer tornadoes in the Southeast U.S. • Massive blizzards in the upper Midwest U.S. • Flooding in the Ohio river valley • California received 2x the normal rainfall which caused flooding and landslides http://elnino.wr.usgs.gov/ http://elnino.wr.usgs.gov/ El Niño related landslides along the California coast.
El Niño Impacts Larger and More Violent Storms • More Powerful Waves • Greater Coastal Erosion
Measuring Coastal Erosion Methods: • Surveys • Aerial Photography • Light Detection and Ranging (LiDAR)
LiDAR • Scanning Laser • Stream of Light Pulses Emitted Side-to-Side • Acquires Location and Elevation Data • GPS Receivers and Satellites used to indicate location as data is collected
LiDAR Advantages • Saves Time, Money, and Manpower • Greater Coverage Area • Water Depth Information • Integrated with GPS/GIS • Capable of mapping steeped sloped regions, shadowed areas, and inaccessible areas (such as mud flats and ocean jetties).
January, 1998 February 1998 Monty Hampton, USGS
Sea cliffs in Pacifica, CA • 13 meters of cliff erosion in one year • 1997-98 El Niño accounted for about 50 years of cliff erosion at this location • 12 houses were condemned • 7 were undercut and fell into the ocean
Southern Pacifica http://coastal.er.usgs.gov/lidar/AGU_fall98/ Northern Pacifica http://coastal.er.usgs.gov/lidar/AGU_fall98/
Analyzing LiDAR Data Landslides River Breakthrough Longshore Transport Overwash
October, 1997 2 http://coastal.er.usgs.gov/lidar/AGU_fall98/display.html April, 1998 http://coastal.er.usgs.gov/lidar/AGU_fall98/display.html
October, 1997 2 http://coastal.er.usgs.gov/lidar/AGU_fall98/display.html April, 1998 http://coastal.er.usgs.gov/lidar/AGU_fall98/display.html
Human Interaction • Erosion is a natural process that is inevitable. Humans can intervene but this only deters erosion to alternate areas. • Examples -Jetties -Seawalls -Groins -Beach Renourishment
Questions? Sources • Griggs, G.B. (2002). Coastal Cliff Erosion in San Diego County. Sea Grant California Coastal Ocean Research, R/CZ-157: 3.1.1998-6.30.1999 • Sallenger Jr. A.H. et al. (2002). Sea-cliff erosion as a function of beach changes and extreme wave runup during the 1997-1998 El Niño. Marine Geology 187, no.3-4 p. 279-297 • Storlezzi C.D. and Griggs G.B. (2000). Influence of El Niño-Southern Oscillation (ENSO) events on the evolution of Central California's shoreline. Bulletin of the Geological Society of America 112, no.2 p. 236-249 • http://coastal.er.usgs.gov/lidar (2/20/07) • http://www.geotimes.org/nov03/feature_LIDAR.html (2/20/07) • http://www.woolpert.com/asp/articles/New_LiDAR_Technology.asp (2/20/07) • http://www.cnn.com/WEATHER/9712/06/el.nino.storm/index.html (2/20/07)